Fix outlet ranges for names with dashes

[sstallion]

This PR addresses a bug in _block_to_list that fails if an outlet name contains a -. The following changes will attempt to treat any block element that contains a - as a numeric range. If there is an issue converting this to a numeric expression, it is then treated as a string.

This is particularly useful for me since my outlets are named after the hostname for the machine under control. This comes in handy during development when I need to cycle a machine using dlipower cycle hostname-with-dashes.